Grinding machine



Dec. 12, 1933. J. D. SCAIFE GRINDING MACHINE Original Filed Jan.

16, 1929 3 Sheets-Sheet 1 Ease/ b QDqson gauge 381, %W

Dec. 12, 1933. $A|FE 1,938,933

GRINDING MACHINE Original Filed Jan. 16, 1929 3 Sheets-Sheet 2 zlose ab jl son scaige Dec. 12, 1933. J. D. SCAIFE 1,938,933

GRINDING MACHINE Original Filed Jan. 16, 1929 3 Sheets-Sheet 3 fl C:

ml 54 I, o 3 a l- W O 40 Joseph sedge Patented Dec. 12,1933

GRINDING MACHINE Joseph Dyson Scaife, Leamington Spa, England, assignor to The Heald Machine Company, Worcester, Mass., a corporation of Massachusetts Originalapplication January 16, 1929, Serial No. 332,859, and in Great Britain January 20, 1928. Divided and this application March 4, 1932.

Serial No. 596,773

6 Claims.

The present invention relates to grinding ma chines, particularly to that type known as oscillating raceway grinding machines. In such machines, the workpiece is continuously rotated upon its own axis and is at the same time swung or oscillated through an arc of a circle about an axis whichin the case of a ball race is arranged to be tangential to the locus of the center of curvature of radial sections of the raceway to be 19 ground and is perpendicular to the plane of contact between wheel and workpiece which contains the center of the wheel; whilst the grinding wheel itself is rapidly rotated upon its axis and is so mounted as to be capable of being moved into and out of engagement with the workpiece to effectgrinding thereof. This application is a division of my copending application Serial No. 332,859, filed January 16, 1929, upon which application United States Patent No. 1,856,227 was granted on May 3, 1932, and

relatesgenerally to the wheel-dressing or Wheeltruing arrangements and instruinentalities set forth and described in said parent application.

In order that the invention may be more clearly understood and readily carried into effect, reference may now be had to the accompanying drawings, which illustrate the inventionby way of example, and in which Fig. l is a front elevation of apgrinding machine constructed according to the invention, part of the base of the machine beingv broken away in order to more clearly show the operation of certain mechanism, and the truing mechanism being omitted from this view. Fig. 2 is a plan view of the machine.

, Fig. 3 is a fragmentary rear elevation on an enlarged scale, showing the mechanism for bringing the truing device intotruing position.

Fig. 4 is a fragmentary elevation of the truing mechanism as seen from the left hand end of the machine, the parts being shown on the same scale as Fig. 3.

Fig. 5 is an isometric View of the actuating mechanism formoving the wheel in cutting relation to the work, these'parts being'shown as detached from the machine.

Fig. 6 is a sectional view taken on the line 6-6 of Fig. 1.

Like reference characters refer to like parts 0 throughout the drawings Referring first to Figs. 1, 2 and 6 of the accompanying drawings, the reference numeral 1 indicates the work head or head stock. The head l provides journals for a horizontally disposed row 5 tatable shaft 2. The head 1 is carried bya platform 3 adapted for oscillatory movement about a vertical axis 4. For this purpose the platform 3 has a shaft 5 associated therewith either integrally or otherwise, said shaft being rotatably mounted in suitable bearings such as ball bearings 6 mounted on the machine frame. Suitable slides 7 and 8, preferably disposed at right angles to one another, are provided upon the platform 3, so as to permit the horizontally disposed shaft 2 to be moved into any desired position. The shaft 2 is provided at one end with a face plate 9 to which the workpiece may be secured in any desired manner, and also has a pulley 10 mounted thereon to accommodate a driving belt, not shown, whereby the shaft may be rotated.

At the right hand side of the machine, as viewed in Figs. 1 and 2, is a slide or carrier 11, which is mounted upon the machine frame or bed in such a manner that it is adapted to be moved in a horizontal plane longitudinally of the ma- [5 chine towards and away from the head 1; For this purpose, the carrier 11 may be provided with suitable guiding means between itself and the machine frame, and also with a rack 12 co-operating with a gear 13suitably mounted upon the machine frame, the gear being adapted to be rotated by means, for example, of the handle 14 and attached pinion 14', to cause movement of the carrier 11 with respect to the frame.

Various elements and mechanisms are mounted upon the carrier 11 and these will now be described in detail. Firstly there is a slide 15 adapted for movement transversely of the machine frame. Referring to Figs. 1, 2 and 5, movement may be imparted to the slide 15 by a connecting rod 16, which is pivotally connected to a portion 17 provided by the slide at one end 18, and which is pivotally connected at its other end to an element 20a;

Referring now to Figs. 2 and 5, the driving mechanism for the element 20a which is shown as a disc. is generally designated by the numeral 19. The'element 20a is adapted to be rotated manually from a handle 21, associated with a hand wheel 210., or by power from a pair of stepped pulleys 22a and 22b, the former of which is driven at a constant speed from any suitable source of power. By selecting appropriate opposite grooves in the stepped pulleys 22a and 22b for a connecting belt, not shown, various speeds may be imparted to a shaft 19a which is detachably secured to the pulley 22b bymeans of a clutch 220. The shaft 19ahas a worm 19b fastened thereto which drives a wormwheel 19c, and the latter is fastened to a shaft 19d and pro- 1 gltudinally ofthe machine.

vides also a worm 19c, which is in mesh with a large worm wheel 19] that is mounted on the same shaft 19g as the element 20a; Likewise fastened to the shaft 199 isa worm wheel 211) which is in mesh with a worm 210011 a shaft 21d to which is fastened the hand Wheel 21a. The

worms 19b, 19c and 210 are of steep pitch so" that they will either drive the various worm wheels with which they are in mesh, or be driven therefrom. V

The connection 20 between the element 20a and the connecting rod 16 is eccentric to the axis of revolution of the element 20a, which axis is the same as the axis of the shaft 199. Thus, in effect, this connection 20 is a crank, the throw of which determines the movement of the slide 15 as the element 20a is rotated.

Upon the slide 15, and also adapted for movement transversely of the machine with respect to the slide 15, is mounted a slide 23 which carries a suitable journal. 24 for a horizontally disposed grinding wheel shaft 25 which is adapted to be rapidly rotated in any convenient manner, for example, by means of a belting applied to the pulley 25a.

At one end the slide 23 has associated therewith mechanism-shown in Figs. 1 and 2--by means of which it may be moved transversely of the machine frame relatively to the slide 15. This mechanism may comprise a ratchet wheel 26 mounted upon a shaft 25 journalled in an element 28 attached to the slide 23, said shaft being provided with a screw thread adapted to mesh with a co-operating nut element 29 associated with the slide 15 in such a manner that rotation of the shaft 2'? causes corresponding movement of the slide 23. A finger 30, carried by an arm 31 which is rockably mounted upon the shaft 27, is adapted to co-operate with an. inclined surface or cam 32, mounted upon the machine frame, during movement of the carrier 11 longitudinally ofthe machine. The'arm 31 also carries a pawl or pawls 33 adapted to co-operate with the teeth of the ratchet wheel 26 to cause rotation thereof, and consequently of the shaft 27, to move the slide 23 with respect to the slide 15 as and for a purpose which will be explained hereinafter.

According to the invention, the improved machine is provided with mechanism for truing the peripheral surface of the grinding wheel or the like while a fresh workpiece is being, set up in the machine, andthis mechanism may,.if desired, be brought into and thrown out of operation automatically during movement ofthe carrier lon- I will now proceed to describe one form of truing device which may be used, butit is to be understood that any other suitable device may be employed.

Asshow'n in Figs. 3 and 4, a pin or projection 34 is attached to the machine frame at the rear thereof, and said pin cooperates with a pair of arms 35 on one arm of a bell crank lever 36 which latter is .secured to a pin 37 pivotally mounted in a depending bracket 37 secured to the carrier 11. The end of the bell crank lever 36 opposite. the arms 35 (which are in parallel relation) is connected by of a rod 39 to an arm 40, the connections 38 and 38a being universal joints. The arm 40 is attached to a support or arm 43 for a diamond or like truing device 44, to swing the truing device 44 up and down about the axis 41.

The truing device 44 is mounted in a suitable holder 45 which'is journalled in 'a bearing portion 46 provided by the arm 43, so that the truing device 44 may be oscillated. That portion of the holder 45 which contains the diamond or other truing device is offset from the axis of oscillation of the holder, so that the point ofthe diamond may face the center of oscillation. In order to oscillate the holder 45 about its axis 47, the arm 43 supports a suitable prime mover 48, for example, a Pelton Water motor, although obviously an electric motor could as well be used. Upon the shaft 49 of the prime mover 48 is a worm 50, said worm meshing with a worm wheel 51 that is rotatably mounted upon an extension of the arm 43. Attached to the top of the worm wheel 51 is a pin 52, and a link or arm 53 connects this pin to a pin or lug 54 provided by the holder 45. Rotation of the wheel 51 therefore causes oscillation of the holder45 about the axis 47. The water or other elastic fluid for the Pelton wheel 48 is supplied by means of a flexible pipe 55, and a valve 56, which controls the flow of fluid to said Pelton wheel is suitably fastened to the carrier 11, Fig. 2, in alinement with the pin or shaft 37. The valve stem, in the construction shown, is an integral extension of the shaft 37 so that the valve is opened for admission of fluid to the Pelton wheel during movement of the carrier 11 to the right at the same time that the dressing tool is moved into operative position. The flow of fluid to the Pelton wheel is cut off during movement of the grinding wheel into operative position by engagement of the arms 35 with the pin 34 which also rocksthe truing device into inoperative position. Fluid is thus supplied to'the Pelton wheel only while the truing device is in operative position.

For the purpose of imparting oscillatory movement to the headstock 1, the vertical shaft 5 has fastened thereto a suitable arm 5a, shown in Fig. as extending from a split collar 5?), and the arm 5:: is connected by means of a link rod 5'7 with a crank or the like 58 which is mounted on the top of a shaft 58a. The shaft 58a is suitably journalled in the machine and received inside of a sleeve 531'). See Fig. 1. On the bottom of the shaft 58a is keyed a movable collar 580, the top portion of which consists of a clutch element for engagement with corresponding clutch teeth provided by the sleeve 58b. Fastened to the sleeve 53b and surrounding it is a worm wheel 58d, which meshes with a worm, not shown, on the end of a shaft 53. The outer end of theshaft 59 is supported by a bearing bracket 60 depending from the side of the machine frame, and stepped pulleys 61 are fastened to said shaft adjacent the bracket 60. By means of the pulleys'61 and oppositely arranged stepped pulleys 62 and a drive pulley 64, the last two being located on a countershaft 63, theshaft 59 may be driven at any desired speed.

A handle 65 and a crank or the like are provided to raise and lower a connector 65a, the lower end of which is pivotally attached to a lever 65b which operates the clutch collar 580. In this manner, the shaft 58a can be stopped and started, thus to control oscillation of the shaft 5 and the head 1.

Having described the principal parts of the improved machine necessary for an understanding of my invention, Iwill now proceed to describe the manner of operation during grinding 'ofa series of ball r'aceways. f

In setting up the machin'efthe workpiece'is l (in secured. in a chuck, not shown, attached to the face plate'9 in any appropriate manner, and the shaft2 is then adjusted by means of the slides 7 and 8.until the axis 4 of the vertical shaft 5 is tangential to the locus of the center of curvature of the raceway to be ground. The slides '7 and 8 are then secured in their adjusted positions. During this operation, the headstock is stationary, the'clutches inthe driving means for the shaft 5 and also for the shaft 2 being at this time disengaged. I

. Assuming a grinding wheel 66 to have been mounted upon theshaft 25, the clutches are now engaged, thus imparting to the workpiece oscillation about the axis 4 and rotation about the axis 2, and the operator rotates the handle 14 which has the effect of moving the carrier 11 and consequently the grinding wheel 66 mounted upon the :shaft 25 longitudinally of the machine towards the workpiece. During this forward move ment of the slide, the power supply of the prime mover 48 is automatically cut oif when the arms of the bell crank lever 36 contact with, and are rocked by, the pin 34 on the frame. The bell crank lever 36 is therefore rocked about the axis of the shaft 37 and through the connection v39 a downward movement is imparted to the free end of the arm 40 which causes the outer end of arm 43 to swing upwardly about the pivot 41 to raise the truing device 44 and associated parts to an inoperative position.

The longitudinal movement of the carrier 11 is continued until the plane passing through the center of the grinding wheel and perpendicular to its axis contains the vertical axis 4, the carrier being stopped in this position by suitable stops thereon engaging co-operating stops on the frame of the machine. These stops are, of course, adapted to be adjusted according to the size of grinding wheel and workpiece set up in the machine.

The handle 21 is now manually operated to cause the slide 15 and the elements and mechanism associated therewith or carried thereby to be moved transversely of the machine through the crank motion and connecting rod 16; this movement continuing until the grinding wheel just engages the work. At this point, the clutch 220 in the driving mechanism 19 of the slide 15 is engaged, and the slide 15 is driven by power until the grinding operation has been completed, when the clutch 220 is disengaged and the grinding wheel withdrawn clear of the work by manipulation of the handle 21. It will be understood that during the whole time of engagement between the workpiece and the grinding wheel, the former is being oscillated continuously about the axis 4 through the driving connections previously described. The throw of the crank motion in the drive of the slide 15 determines, of course, the travel of the slide 15 and consequently the maxi- 'mum diameter of the raceway being ground.

As soon as the actual grinding operation has been. completed, oscillation of the shaft 5 is stopped by manipulation of the handle 65, and the carrier 11 is moved longitudinally of the machine to withdraw the grinding wheel out of the workpiece by manipulation of the handle 14.

During this movement of the carrier 11, the finger 30 rides up the inclined surface or cam 32 to rock the arm 31 and consequently the pawl or pawls 33 upwardly. The effect of this is to rotate the ratchet wheel26 and shaft 27, causing movement of the slide 23 transversely of the machine and relatively to the slide 15. This movement is calculated to be equivalent, to that required to compensate for the wear on the grinding wheel during the preceding grinding operation and in the machine shown is sufficient also to permit an amount of material to be removed from the grinding wheel by the truing device 44.

The truing device 44 is brought into operation during the movement of the carrier 11 away from the head 1 by the arms'35 of the bell crank lever 36 moving out of contact with the projection 34 on the frame of the machine. It should be noted at this point that the arm 43, the prime mover 48, oscillating member 45 and the other parts of the truing mechanism, including the arm 40, are raised by the movement of the carrier ll to carry the grinding wheel to grinding position, so that their combined center of gravity has moved beyond the vertical plane of the pivotal axis 41. Thus the weight of these parts, during the grinding operation, does not tend to move the carrier 11 to carry the wheel 66 out of grinding position, but rather tends to hold it there against the stops before mentioned. The subsequent movement of the carrier 11 to carry the wheel out of position after a grinding operation causes positive movement of the truing mechanism in a clockwise direction, Fig. 4, by reason of the fact that the pin 34 fits between the arms 35, 35. The provision of these two arms also insures the movement of the truing mechanism without shock, and permits it to be lowered to the position shown in Fig. 4, where it rests against stops, not shown. At the same time the operation of the prime mover 48 for oscillating the diamond truer, in this case the Pelton wheel, is initiated by turning of the shaft 37 with the result that the diamond holder 45 is oscillated about its axis 47 through the connections and in the manner already described to true the grinding wheel. The truing operation serves to maintain the cutting side of the grinding wheel, at the moment of greatest advance of the slide 23, tangent to a fixed vertical plane that is parallel to the motion of the carrier 11, by reason of the fact that the whole truing mechanism is carried by the carrier 11 and slide 23 and is always oscillated about the same axis 47. The compensating mechanism shown in Fig. l and already described, which causes a slight movement of the slide 23 on the slide 15 after each grinding operation serves to advance the grinding wheel towards the dressing device 44 by small increments for each grinding operation to insure contact between them. As the grinding wheel is always brought to the same position laterally of the machine by the connecting rod 16 and the actuating mechanism 19, uniform size of successive workpieces is insured.

During the truing operation, the previously ground workpiece is removed from the machine and a new one substituted therefor, the operation of the machine as already described being then repeated.

Owing to the fact that the slide is positively moved to effect grinding by means of a crank motion, a coarse feed is, provided at the commencement of the grinding operation, and the feed is reduced gradually during the grinding operation until at maximum stroke of the crank it is zero, thereby enabling a very smooth finish to be obtained upon the workpiece.

In order to insure correct action of the machine and to procure precision despite possible lost motion in some of the connections operating the slide 15, means is provided to urge the slide in one direction or the other to take up any such lost motion. This means is shown in Fig. 3 and comprisesa shaft 71 which is given a torque by means of a spring '72, an arm 73 being fastened to the end of the shaft 71, and the upper end of said arm being attached by a pin and fork connection '74 to the slide 15.

Although in the foregoing I have described but one particular embodiment of my invention, it is to be understood that many variations may be made therein-without departing from the spirit and scope of the invention as defined in the accompanying claims.

I claim:'

1. In a grinding machine, the combination with a grinding wheel and means to rotateit, of a truing device comprising a diamond or like truing tool, an oscillatable member carrying said truing tool with its point facing the center of oscillation, a pivotally mounted supporting member for the oscillatable member, a motor mounted on said supporting member to oscillate the truing tool, a carrier to carry the grinding Wheel into and out of grinding position, and means operated by movement of said carrier to move said supporting member to carry said truing tool into and out of truing position.

2. In a grinding machine, the combination with a grinding wheel and means to rotate it, of a truing device comprising a diamond or like truing tool, an oscillatable member carrying said truing tool with its point facing the center of oscillation, a supporting member for the oscillatable member, a motor mounted on said supporting member, and connections between said motor and said oscillatable member to oscillate it and the truing tool, said connections including reducing gearing and an eccentric connection.

3. In a grinding machine, a grinding wheel having a peripheral cutting surface of the second order, that is circular about a main axis of rotation and curved in a transverse plane, a carrier to move said grinding wheel into and out of grinding position, a cross slide mounted on said I carrier, means for moving said cross slide'to produce a cutting action, a truing mechanism comprising a truing tool, an oscillatable member carrying said truing tool with its point facing the center of oscillation, and means to oscillatethe said member, carrying means for said truing mechanism permitting it to be moved into and out of truing position, and supporting means for said carrying means mounted upon said cross slide, whereby to preserve correct alinement between the center of oscillation of the truing tool and the grinding wheel and to allow the grinding wheel to be trued irrespective of the position of said cross slide. a

4. In a grinding machine, a grinding wheel, a carrierto move said grinding wheel into and out of grinding position, a truing tool, an oscillatable member carrying said truing tool with its point facing the center of oscillation, a second oscillatable member holding the first oscillatable member to swing the truing tool completely away from truing position, power means to oscillate the truing tool, and means operated by said carrier for swinging the truing mechanism into truing position and for causing oscillation of the truing toolwhen the carrier carries the grinding wheel to an operative position, and for swinging the truing mechanism out of position and stopping oscillation of the truing tool when the carrier returns the grinding wheel to grinding position.

5. In a' grinding machine, a grinding wheel having an arcuate cutting surface transverse to its axis of rotation, a dresser for said surface, means to procure a feeding movement between said Wheel and a workpiece comprising a crossslide, means for advancing said slide to a predetermined point during each successive grinding operation, and means to compensate for the reduction in size of the wheel as a result of dressing operations and wear on the wheel so that the cutting locus of the surface of said wheel shall be tangent to a predetermined plane at the end of each successive grinding operation.

6. In a truing mechanism for a grinding wheel having an arcuate cutting surface transverse to its axis of rotation,,a truing tool, power means to oscillate said tool, means to move said tool into and out of truing position, and means operated by said last named means to cause said power means to oscillate said tool.

JOSEPH DYSON SCAIFE. 

